This invention relates generally to magnetic resonance imaging (MRI), and more particularly the invention relates to the use of MRI for the determination of hemodynamic parameters particularly in patients suffering from strokes.
Dynamic susceptibility contrast weighted (DSC) magnetic resonance perfusion imaging (PWI) promises to allow rapid assessment of hemodynamic parameters in stroke patients, which would allow better assessment of tissue viability and outcome prediction of stroke patient. In concert with diffusion weighted/diffusion tensor imaging, DWI/DTI, patients could be triaged on the basis of information derived from such quantitative perfusion measurements. This would have important implications for the treatment of stroke patients, since reperfusion therapy is only effective within the first few hours after the onset of stroke and can increase the mortality rate due to hemorrhagic transformation in later, more severe strokes. Unfortunately, in practice, DSC-PWI usually has limitations. Besides geometric distortions and poor resolution of EPI scans, there are considerable problems in accurately determining an arterial input function (AIF), which is required to determine the tissue residue function by deconvolving the tissue response signal with the AIF. Frequently, the internal carotid arteries (ICA) and parts of the initial branches of the anterior or the middle cerebral arteries (ACA, MCA) are difficult to depict or are contaminated by partial volume averaging.
The prior art suffers from strong signal saturation effects during the peak of the contrast agent bolus passage. Thus, the concentration of contrast material during this phase is underestimated and the arterial input function (AIF) that is deconvolved with the brain tissue response in each voxel is in error.
The present invention is directed to DSC-PWI with improved image quality and quantification capabilities.